Method of making mirrors having randomly reflective decoration

ABSTRACT

There is provided a method of providing decoration of predetermined pattern between the inner glass surface and the silver surface of a mirror. This decorative pattern permits the partial or substantially total passage of light therethrough while changing the direction of the light rays to give rise to a very bright crackle effect, which may, if desired, be additionally colored. In the process of the present invention a thin plastic film in a suitable solvent is placed upon a glass sheet, and heated in a predetermined manner prior to said surface being coated with a silver reflective surface in the usual manner.

[ Jan. 21, 1975 METHOD OF MAKING MIRRORS HAVING RANDOMLY REFLECTIVE DECORATION [75] Inventors: Sidney Ashenfarb, Roslyn; Marvin Weinblatt, Flushing, both of N.Y.; Leonard F. Glowzenski, Middletown, NJ.

[73] Assignee: New Age Mirror And Tile Industries, Inc., Newark, NJ.

[22] Filed: Jan. 28, 1974 [21] Appl. No.1 437,088

[52] US. Cl. 161/4, 117/35 R, 117/41, 117/71 R [51] Int. Cl. B44f l/00, B44f 3/00 [58] Field of Search 161/4; 117/35 R, 71 R, 117/41 [56] References Cited UNITED STATES PATENTS 2,464,143 3/1949 M artinson et al ll7/35 R 9/ 1954 Pessel 8/1956 Gerlach Primary ExaminerMayer Weinblatt Assistant Examiner--Edith L. Rollins Attorney, Agent, or Firm-Omri M. Behr [57] ABSTRACT There is provided a method of providing decoration of predetermined pattern between the inner glass surface and the silver surface of a mirror. This decorative pattern permits the partial or substantially total passage of light therethrough while changing the direction of the light rays to give rise to a very bright crackle effeet, which may, if desired, be additionally colored. 1n the process of the present invention a thin plastic film in asuitable solvent is placed upon a glass sheet, and heated in a predetermined manner prior to said surface being coated with a silver reflective surface in the usual manner.

12 Claims, 3 Drawing Figures FIG. 1

hum 1.,

FIG. 2

FIG.3

PATENIED JAN 2 I I975 METHOD OF MAKING MIRRORS HAVING RANDOMLY REFLECTIVE DECORATION DESCRIPTION OF THE PRIOR ART It is well known to produce reflective surfaces upon glass. In the generally accepted procedure, the glass surface is cleaned, washed with a wetting agent and an aqueous solution of a salt higher on the electrochemical series than silver. The wet plate is then treated with a dilute solution of silver nitrate whereby the silver is precipitated upon the glass forming a reflective surface. It is customary to protect this surface by depositing thereon a thin layer of copper in the manner well known to the art, drying the copper coating and laying thereon a protective coating of a suitable paint.

It is also well known in the art to place patterns between the coated glass surface and the reflective surface by painting or printing a pattern thereon. These patterns may be opaque or translucent as desired. Since metallic paints are known these also may be employed and have been employed in order to impart to the printed pattern a randomly reflective surface. This ramdomly reflective surface however due to the extremely small size of the particles in the metallic paint does not provide a pattern having a reflectivity of the same order of magnitude as the main reflective surfaces of the mirror and therefore, do not have as bright an appearance as the background.

It has been deemed desirable in the decorative field to provide a decorated mirror having a decorative pattern thereon where the decorative surface is randomly reflective and reflective in the same order to magnitude as the general background of the mirror as a whole. Certain processes for a totally random decorative effect of this type have been developed as disclosed, for example, in Gerlach, U.S. Pat. No. 2,757,473. Unfortunately, the Gerlach process does not give rise to an ornamentation of a high degree of random reflectivity.

A study of the Gerlach process discloses that its manner of operation depends upon either the mere interposition of a paint layer between the glass and the reflective surface or a weakening of the reflectivity by the introduction of an interfering material into the reflecting layer.

Heretofore, it has not been possible to provide a pattern of substantially random reflectivity which has substantially the same degree of reflectivity as the principal reflective surface of the mirror and which may, if desired. also be tinted.

SUMMARY OF THE INVENTION In the process of the invention there is prepared a coating comprising an alkyd resin, an epoxy resin, suitable solvents, and, if desired, a suitable pigment. A thin layer of this coating is laid upon one surface of a glass sheet. The coated sheet is then heated to remove the solvent, cure the resins, and leave a stable, but crackle finish in the coating. The entire coated surface is then silvered in a manner well known to the art. If no pigment is utilized then the crackle finish has substantially the same reflectivity as the main reflecting surface. If a pigment is used then the degree of reflectivity will be reduced by a small amount due to the presence of the pigment.

DESCRIPTION OF THE DRAWINGS FIG. 1 shows a plan view of a glass sheet having a design thereon prior to curing. 5 FIG. 2 shows a cross-section of the completed mirror (layers not to scale).

FIG. 3 shows a plan view of the mirror of FIG. 2 viewed from 3--3 showing the appearance of the mirror and an object (an apple) reflected therein.

DETAILED DESCRIPTION OF THE DRAWINGS The mirrors produced by the process of the present invention comprise a transparent glass sheet I having a front face I6 and a rear face I2. Upon a predetermined portion of rear face I2 is placed a predetermined design 14 in accordance with the more detailed procedures described hereinbelow. This design 14 gives rise to a highly reflective random effect and may, if desired, be pigmented, also in accordance with the more detailed description hereinbelow.

A reflective surface 22, which may be either silver or aluminum cover surface 12 and the exposed portions of decorative design 14 which are not in Contact with face 12 of plate 10. Rearwardly of reflective layer 22 is, optionally, a layer of copper 24 which is backed by a protective paint layer 26. The total effect may be seen in FIG. 3, wherein the randomly reflective layer 14, as view in direction 3-3 of FIG. 2, partially obsecures the clear reflection of an object, i.e., an apple, which is placed in front of the said mirror.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The process of the present invention is carried out utilizing a pre-prepared resinous coating to form a design and clean glass sheets. While the descriptions set forth hereinbelow relate to planar glass sheets, the invention is not restricted thereto and the procedure set forth herein may be readily utilized for curved glass sheets. The coating composition is conveniently designated a 2-part composition although it is combined when used. The first portion comprises an alkyd resin preferably an orthophthalic alkyd resin, most preferably a melamine modified orthophthalic alkyd resin, suitable solvents, and, if desired, pigment. In the preferred embodiments of the invention, there are utilized between 42 and 51% by weight of the alkyd resin. Where no pigment is utilized, there are used between 48 and 53% resin. It is especially preferred to utilize approximately 43.9% resin when a pigment is used and approximately 51% resin when no pigment is used. The amount ofpigment utilized will depend upon the intensity of the coloration required. This, of course, is a matter somewhat within the discretion of the designer of the articles. Between 1 and 8%, suitably between 6 and 8%, most preferably 6.5 to 7.5% of pigment are utilized. Any pigments utilized in the paint arts may be utilized, the only important proviso being that they be extremely finely ground, that is to say, they should be ground to a fineness of between about to about 7, preferably 6 to 7 on the Hegman Scale. Where design requirements call for a slight obscuring of the reflective layer titanium dioxide may be added to the pigment. It is to be expected however that most of the uses to which the process of the present invention is put will call for maximum transmittance thru the decorative layer and thus merely pigment such as CP Chrome Yellow, Phthalocyanin Green, and the like will be employed since the use of pigment without titanium oxide leads to the maximum brightness in any colored decorative layer.

Where pigments are employed, it is desirable to use a mixture of alkanolic and aromatic solvents. It is desirable that the solvents should have different boiling ranges. Thus, one solvent should have a boiling point in the range of, say, 80 to IC, and the other solvent should have a boiling point in the range of, say, 120 to 150C. The specific boiling points are not critical. Thus, for example, where a pigment is utilized the alkanol suitably a lower monohydric alkanol may be isopropanol having a boiling point of about 84C and the aromatic solvent may be orthoxylene having a boiling point of approximately I44C.

Where no pigment is utilized, it has been found helpful to utilize a slightly different solvent system. Thus, there is utilized a mixture of alkanols, for example, methanol and isopropanol and a higher boiling solvent, suitably butyl ether of diethylene glycol.

Where a pigment is utilized, it is desirable to employ between about 7 to about 8% of the alkanols, suitably about 7.3 to about 7.5% of alkanols and from about 38 to about 42% of the aromatic solvent, suitably from about 41.5 to about 42.5%.

Where a pigment is not employed, it has been found desirable to utilize from about 14 to about 17%, suitably from about 16 to about 17% of methanol, from about 7 to about 9.5%, suitably about 8.5 to about 9% of isopropanol, and from about 21 to about 25% suitably about 2324% of the monoalkyl glycol ether, preferably monobutyl ether of diethylene glycol.

The second portion of the coating mixture comprises an epoxy resin in a suitable solvent. There may be employed from about 48 to about 53%, preferably from about 52 to 53% of the epoxy resin. The solvent portion is again a 2-part system comprising butyl ether of dicthylene glycol and an aromatic solvent. As an aromatic solvent there may be employed a petroleum frac tion having a boiling point lying in the range of between 180 and 215C. A suitable solvent in this range is Espesol (2), (registered trademark of Charter Chem. Co.). The second component is a monoalkyl ether of ethylene glycol, suitably the monobutyl ether. There are employed between 30 and 34, preferably from about 33 to about 34% of the aromatic solvent and between about 12 to about 16%, suitably about l2 to about of the ether.

There may be employed between 100 to 200 parts of the first component of the coating composition to each 100 parts of the second component of the coating composition, suitably, there are employed 150 parts of the first component to 100 parts of the second component. it is desirable to place the coating composition in a thin layer upon the glass. The effect obtained however will depend upon the thickness of the coating. Thus, if the coating is less than 0.75 mils in thickness, only a wrinkle effect will be noticed. The much sought after crackle effect will not usually be found. On the other hand, if the thickness of the coating is in excess of 2 mils. then pin-hole effects will also be found. The most desired crackle plus wrinkle effect will be found utilizing initial thickness range of between 1.25 to about 1.75 mils, most suitably about 1.5 mils. These thicknesses refer to wet film thickness.

Any convenient method of coating may be employed. However, it has been found that silk screening is the most prefered mode giving the best control of thickness. Where silk screening is utilized it is preferred to utilize a mesh of 200 to 100 mesh, most suitably about 120 mesh per square inch.

The coating on the glass is then cured. It is preferred however to permit a proportion of the lower boiling solvents to flash of before the high temperature curing step. The coated glass is thus permitted to lie at ambient temperature for from about I to about 2 minutes.

The coated glass is then briefly cured at elevated temperatures. Time, of course, standing in inverse relationship to temperatuare. Thus, the cure may proceed for about 20 seconds, from about 375 to about 450F. or for about 30 seconds at from about 300 to about 375F, a temperature range of from about 300 to about 350F being preferred. This cure gives rise to a wrinkled appearance of the coating combined with a crackle effect, that is to say, the appearance of divisional lines randomly placed in the coating.

The glass having the cured coating thereon is then silvered in the manner well known in the art. In this procedure the coated plate is washed with a wetting agent, preferably an anionic wetting agent, suitably of the sulfonic acid type. ln order to achieve a high polish on the surface it is preferred to follow this wash with a polishing step with .lewelers Rouge, removing the Jewelers Rouge with water and soaking the surface to be silvered with an aqueous solution of stannous chloride. It is generally preferred that the stannous chloride have a concentration of between 4 and 8, suitably about 6 ounces of stannous chloride per lOO gallons of water.

The plate is then treated with a standard silvering solution comprising a caustic component consisting of water, sodium hydroxide, and a silver nitrate portion consisting of distilled water, silver nitrate, and ammonium hydroxide. It is preferred to spray a mixture of the caustic and silver nitrate solutions onto the glass plate followed by a precipitant solution consisting of distilled water and granulated sugar. The foregoing solutions are well known in the art and the invention should not be considered to be limited thereby since other solutions achieving the same effect may be utilized.

The excess silvering solution is removed by air blowing followed by a water rinse.

A thin layer of copper is then precipitated upon the freshly prepared silver layer by washing with a dilute aqueous solution of copper sulfate containing from about 30 to about pounds of copper sulfate in l00 gallons of water containing about 3050 fluid ounces of concentrated sulfuric acid. This precipitation is achieved by spraying the silver layer simultaneously with the acidic copper sulfate solution and a separate spray of zinc dust (30-70 ounces) and formaldehyde, 60-90 ounces per gallons of water.

The mixed sulfate solution is then again removed by water wash followed by blowing with hot air, and the copper layer covered with a protective layer of paint which is then baked on to provide a permanent coating.

It should be noted that the inventive steps ofthe present invention are considered to be those concerned with the placing of decorative coating upon the glass surface while those concerned with silvering the cured decorated surface are steps well known in the art. Decorated mirriors having, say, aluminum reflective layers vacuum deposited thereon should be considered within the scope of this invention.

Where the reflective coating is achieved by vacuum deposition of, say, aluminum, a slightly different procedure than that set forth hereinabove is utilized. The decorative coating is placed on the glass in the manner stated heretofore but the preparation of the glass having the cured coating thereon omits the step of washing with a wetting agent prior to polishing with Jewelers Rouge.

After the Jewelers Rouge is removed by washing with water, the glass is dried, suitably by means of hot air blown over the surface thereof, the cleaned glass is placed on racks adapted for use in vacuum deposition apparatus.

The racks are then placed in the vacuum deposition apparatus which is then evacuated and the appropriate metal, for example, aluminum, vaporized and deposited in the usual manner.

The vacuum is then broken, the metalized glass removed from the racks and a protective layer, suitably a layer of paint is placed on the exposed portion of the metal reflecting surface, thereafter the paint is cured, suitably by baking to provide a permanent coating.

EXAMPLE 1 150 parts by weight ofCrystalustre Goldcoat Component A (trademarked product of Maas and Waldstein Co., Newark, NJ.) are mixed with 100 parts of Crystalustre Component B (trademarked product of Maas and Waldstein Co., Newark, N.J.).

Component A comprises:

Melamine Modified Orthophthalic Alkyd 43.89% wt.

Red Pigment 6.7% wt.

lsopropanol and Xylene (:85) 59.41% wt.

To Component A there is added 100 parts of Component B consisting of:

Epoxy Resin 52.65% wt.

Espesol (2) Aromatic Solvent, and

Monobutyl Ether of Ethylene Glycol (7:2) 47.35%

The mixed components are applied thru a silk screen of 120 mesh bearing a predetermined design onto a flat glass surface leaving a thickness of approximately 1.5 mils thereon.

The coated glass is maintained at ambient temperature for approximately 1.5 minutes and heated in a well ventilated oven for seconds in a temperature range of 335 to 350F. In accordance with the foregoing procedure but in place of using Goldcoat Component A there may be utilized Chrome Coat Component A consisting of:

Melamine Modified Orthophthalic Alkyd 51% wt.

Methanol/lsopropanol/Diethylene Glycol Monobutyl Ether (:18:48) 49% wt.

There is thus obtained a clear unpigmented coating.

ln accordance with the procedures set forth in the principal part of the foregoing Example, any color of pigment may be employed to provide a decorative coating of the desired coloration.

EXAMPLE [1 Silvering Step The coated glass is then subjected to the following steps:

a. washing with water containing 2% by weight of RBL wetting agent (manufactured by the London Laboratories, Woodbridge, Conn.).

b. polishing with a suspension of .lewelers Rouge, (Ferric Oxide 8-12 pounds and Cerium Oxide 24 pounds per 50 gallons of water.)

c. water washing.

d. spray with stannous chloride (6 ounces per 100 gallons of water).

e. rinse with water.

f. spray with a spray consisting of a mixture of caustic and silver nitrate solutions having the following composition:

Caustic:

sodium hydroxide 58 ounces per 100 gallons of water.

Silver Nitrate:

Silver nitrate(crystaline) 64 ounces per 100 gallons of water. Ammonium hydroxide (27%) 140 ounces per 100 gallons of water. and, at the same time, thru a separate set of nozzles sprayed with equal volumes of precipitant solution having the following composition:

Dextrose Special hydrate (Corn Products TF8) 133 ounces per 100 gallons of water. I

g. remove excess silver solution by air blowing.

h. water wash i. spray with an equal volume but from separate sources of acidic copper sulfate (CuS O 51 pounds; sulfuric acid 93%, 41 fluid ounces; 100 gallons of water) and aqueous zinc dust suspension (Zn: 51 ounces, formaldehyde ounces, gallons of water).

j. blow off the excess salt solutions.

k. rinse with water.

1. dry with hot air.

m. roll on temperature curable paint.

n. bake on paint.

We claim:

1. A process for the formation of glass mirrors having a reflective decorative pattern thereon comprising the steps of:

i. Applying to said glass surface a thin layer of a solvated mixture of Melamine Modified Orthophthalic Alkyd Resin and Epoxy Resin in a predetermined design, wherein the coating composition consists of 100 to 200 parts by weight of a first submixture consisting of:

a. A Melamine Modified Orthophthalic Alkyd Resin, 42-51%, b. Pigment, 1 to 8%, c. Lower monohydric alkanol,

d. Aromatic Hydrocarbon Solvent; b.p. to

C to a total of 100% and, 100 parts by weight of the second submixture consisting of:

e. Epoxy Resin, 48 53%, f. Aromatic Petroleum Fraction, b.p. -215C, g. Ethylene Glycol butyl Ether; to a total 100%, and

ii. Curing said coated layer and applying a reflecting surface to said coated layer and the exposed portion of the glass on the side thereof bearing the coated layer.

2. A process according to claim 1 wherein the reflecting surface is silver or aluminum.

3. A process according to claim 1 wherein the coating composition is applied thru a silk screen.

4. A process according to claim 1 wherein the coating, prior to curing, has a thickness of between 1 and 2 mils.

5. A process according to claim 1 wherein the coating composition is cured at between 300 and 450F for between 30 and seconds.

6. A process according to claim 1 wherein the mixed resin layer is 1.25 to l.75 mils in initial wet thickness.

the alkanol of Component (c) is isopropanol,

the hydrocarbon of Component ((1) is xylene,

g. butyl ether, and,

the resin layer is cured for 20-30 seconds at 7. A process according to claim 1 wherein the mixed resin layer is 1.25 to 1.75 mils in initial wet thickness,

the alkanol of Component (b) is i. isopropanol, 6-9.5%, ii. methanol l4-l7%,

f. butyl ether, and,

the resin layer is cured for- 20 to seconds at 8. A process for the formation of glass mirrors having a reflective decorative pattern thereon comprising the steps of:

i. Applying to said glass surface a thin layer of a solvated mixture of Melamine Modified Orthophthalic Alkyd Resin and Epoxy Resin in a predetermined design, wherein the coating composition consists of 100 to 200 parts by weight of the first submixture consisting of: a. Melamine Modified Orthophthalic Alkyd Resin,

48 53%, b. Lower Monohydric Alkanol, c. Ethylene Glycol butyl Ether; to a total of 100%; and 100 parts, by weight, of the second submixture consisting of: d. Epoxy Resin, 48-53%, e. Aromatic Petroleum Fraction, b.p. l2l5C,

30-34%. f. Ethylene Glycol butyl Ether, 12-16%; to a total of ii. Curing said coated layer and applying a reflecting surface to said coated layer and the exposed portion of the glass on the side thereof bearing the coated layer.

9. A process according to claim 8 wherein the coating composition is applied through a silk screen.

10. A process according to claim 8 wherein the coating, prior to curing, has a thickness of between 1 and 2 mils.

11. A process according to claim 8 wherein the coating composition is cured at between 300 and 450F for between 30 and 20 seconds.

12. A process according to claim 8 wherein the reflecting surface is silver or aluminum. 

2. A process according to claim 1 wherein the reflecting surface is silver or aluminum.
 3. A process according to claim 1 wherein the coating composition is applied thru a silk screen.
 4. A process according to claim 1 wherein the coating, prior to curing, has a thickness of between 1 and 2 mils.
 5. A process according to claim 1 wherein the coating composition is cured at between 300* and 450*F for between 30 and 20 seconds.
 6. A process according to claim 1 wherein the mixed resin layer is 1.25 to 1.75 mils in initial wet thickness, the alkanol of Component (c) is isopropanol, the hydrocarbon of Component (d) is xylene, g. butyl ether, and, the resin layer is cured for 20-30 seconds at 300*-350*F.
 7. A process according to claim 1 wherein the mixed resin layer is 1.25 to 1.75 mils in initial wet thickness, the alkanol of Component (b) is i. isopropanol, 6-9.5%, ii. methanol 14-17%, f. butyl ether, and, the resin layer is cured for 20 to 30 seconds at 300*-450*F.
 8. A process for the formation of glass mirrors having a reflective decorative pattern thereon comprising the steps of: i. Applying to said glass surface a thin layer of a solvated mixture of Melamine Modified Orthophthalic Alkyd Resin and Epoxy Resin in a predetermined design, wherein the coating composition consists of 100 to 200 parts by weight of the first submixture consisting of: a. Melamine Modified Orthophthalic Alkyd Resin, 48 - 53%, b. Lower Monohydric Alkanol, c. Ethylene Glycol butyl Ether; to a total of 100%; and 100 parts, by weight, of the second submixture consisting of: d. Epoxy Resin, 48-53%, e. Aromatic Petroleum Fraction, b.p. 180*-215*C, 30-34%, f. Ethylene Glycol butyl Ether, 12-16%; to a total of 100% ii. Curing said coated layer and applying a reflecting surface to said coated layer and the exposed portion of the glass on the side thereof bearing the coated layer.
 9. A process according to claim 8 wherein the coating composition is applied through a silk screen.
 10. A process according to claim 8 wherein the coating, prior to curing, has a thickness of between 1 and 2 mils.
 11. A process according to claim 8 wherein the coating composition is cured at between 300* and 450*F for between 30 and 20 seconds.
 12. A process according to claim 8 wherein the reflecting surface is silver or aluminum. 